Variable inductance



Nov. 20, 1928.

N. H. CLOUGH VARIABLE INDUCTANCE Filed Jan. 1925 INVENTOR NEWSOME H.CLOUGH /d(www ATTORN EY Patented Nov. 20, 1928.

UNITED STATES PATENT OFFICE.

-NEWSOME HENRY CLOUGH, OF CHELMSFORD, ENGLAND, ASSIGNOR TO PORATION OFAMERICA, A CORPORATION OF DELAWARE.

RADIO COR- VARIABLE InnUo'rANoE.

Application filed January 3. 1925. Serial No The object of thisinvention is to provide a that it covers varying portions of the coilthe inductance of that coil may be continuously varied.

Alternatively I may wind the inductance in the fashion of a solenoidaround a short cylindrical former and mount a shield in the form of aring so that it can rotate about an axis perpendicular to the axis ofthe former.

The invention is illustrated by the acco1npanying drawing, Figure 1 ofwhich is an inverted plan of a variable inductance constructed inaccordance therewith; Fig. 2 shows a modification in which three coilsof different values of inductance are used; Fig. 3 is a side elevationof another modification;

Fig; 4 is a plan of the modification shown by Fig. 3; Fig. 5 is asectional view of still another modification; Fig. 6 is a view. partlyin section of still a further modification and Fig. 7 is a diagrammaticrepresentation of a switch for connecting in circuit the desiredinductance when the modification shown by F ig. 2 is used.

The coil A is wound upon a former B in the shape of a ortion of asphere, and a metallic shield C su stantially in the shape of ahemispherical shell is mdunted upon a pin-the axis of which coincideswith a diameter of the former B, so that by turning the shield it can bemade to cover a varying portion of the coil and thus the inductance ofthe coil may be varied.

The edge of the shield may be shaped so as give any desired inductancelaw. it is understood that the shield may be placed inside of the coilas well as outside.

An inductanc'e thus constructed has the advantage that inasmuch as thewindings are stationary there is no need to employ a commutator or-slirings, that a rotary control is obtained, and that inasmuch as thedistance between the shield and the winding or windings can be made verysmall, the range of inductance is large.

Figure 2 shows three separate coils A, A A, wound upondifferent-portions of a spher- 401. and in Great Britain January 14,1924.

ical former B with a shield C which is mounted as in the case of Figure1 and may thus be used in conjunction with any one of the three coils A,A A the ranges of inductance of the various coils being different. Asuitable switch may be provided for putting into cirwit that coilwhichcit is desired to use at any time.

Figure 3 is a side elevation and Figure 4 is a plan of a modification,inwhich the coil A is wound in the fashion of a solenoid around a shortcylindrical former E while the shield C is in the form of a ring and issupported on a spindle F by which it can be turned to cover more or lessof the coil. The formerE is carried by a support G, the support havinggrooves in which the former can be slidden. Thus the coil can readily beremoved and replaced by another of a different value. v

, Figure 5 is a section of a modification, in

-which'thecoil A is carried by a frame H,

while the shield C is in the form of a ring and is mounted on a spindleF, the axis of which is inclined at an angle a to the plane of coil A.The plane of shieldC isinclined to the axis of spindle F at an angle [3.As illustrated a and B are each equal to 45 and when spindle F is turned180 the planes of coil A and shield C-will coincide and shield C willlie wholly inside coil A.

Figure 6 is a section partly in elevation of another modification inwhich as in Figure 5 coil A is carried by a supportH but in which theshield C takesthe form of a coil of wire wound on a sphere of insulatingmaterial the ends of the wire being interconnected. The axis of thesphere is inclined at an angle or to the plane of coil A, while the laneof shield C is inclined to the axis of the sphere at an angle )3. Theangles a and B being each equal. to 45, the shield will be whollyoperative when given a turn of 180 Having described my invention what Iclaim is: i

1. A variable inductance com rising at plurality of coils wound upon asp erical former and a spherical cap mounted to turn about a diameter ofthe former to cover varying portions of any of the coils.

2. A variable inductance comprising a plurality of coils wound upon a sherical former and a single shield member or varying the inductance ofany of the coils.

3. A device for varying the inductance of a circuit comprising aplurality of coils of different inductances, each of said coils beingadapted to be separately connected in the circuit, and a shield forvarying the inductance of any of said coils.

4. A device for varying the inductance of a circuit comprising aplurality of coils having different inductances Wound upon a sphericalformer, each of said coils being adapted to be connected in the circuit,and a metallic shield for varying the inductance of the coil which isconnected in the circuit.

5. A variable inductance comprising a plurality of coils Wound upon aspherical former, each of said coils having a different inductance, anda spherical shield member mounted to rotate to cover varying portions ofany of said coils. I

6. A variable inductance comprising three coils arranged so that theiraxes intersect at a common point and a shield mounted on an axisperpendicular to the plane of the axes of the coils and at their commonpoint of intersection, said shield being rotatable to vary theinductance of said coils.

'2'. A variable inductance according to claim 6 in which the coils haveinherently NEWSOME HENRY CLOUGH.

